Spatial–Temporal Correlations between Soil pH and NPP of Grassland Ecosystems in the Yellow River Source Area, China

Xiaoning Zhang, Lili Nian, Xingyu Liu, Xiaodan Li, Samuel Adingo, Xuelu Liu, Quanxi Wang, Yingbo Yang, Miaomiao Zhang, Caihong Hui, Wenting Yu, Xinyu Zhang, Wenjun Ma and Yaoquan Zhang
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Xiaoning Zhang: College of Forestry, Gansu Agricultural University, Lanzhou 730070, China
Lili Nian: College of Forestry, Gansu Agricultural University, Lanzhou 730070, China
Xingyu Liu: College of Forestry, Gansu Agricultural University, Lanzhou 730070, China
Xiaodan Li: College of Forestry, Gansu Agricultural University, Lanzhou 730070, China
Samuel Adingo: College of Forestry, Gansu Agricultural University, Lanzhou 730070, China
Xuelu Liu: College of Forestry, Gansu Agricultural University, Lanzhou 730070, China
Quanxi Wang: College of Humanities and Law, Northeastern University, Shenyang 110169, China
Yingbo Yang: College of Resources and Environmental Sciences, Gansu Agricultural University, Lanzhou 730070, China
Miaomiao Zhang: College of Management, Gansu Agricultural University, Lanzhou 730070, China
Caihong Hui: College of Resources and Environmental Sciences, Gansu Agricultural University, Lanzhou 730070, China
Wenting Yu: College of Resources and Environmental Sciences, Gansu Agricultural University, Lanzhou 730070, China
Xinyu Zhang: College of Resources and Environmental Sciences, Gansu Agricultural University, Lanzhou 730070, China
Wenjun Ma: College of Forestry, Gansu Agricultural University, Lanzhou 730070, China
Yaoquan Zhang: College of Forestry, Gansu Agricultural University, Lanzhou 730070, China

IJERPH, 2022, vol. 19, issue 14, 1-16

Abstract: In recent years, ecological concerns such as vegetation destruction, permafrost deterioration, and river drying have been paid much more attention to on the Yellow River Basin in China. Soil pH is regarded to be the fundamental variable among soil properties for vegetation growth, while net primary productivity (NPP) is also an essential indicator to reflect the healthy growth of vegetation. Due to the limitation of on-site samples, the spatial–temporal variations in soil pH and NPP, as well as their intrinsic mechanisms, remain unknown, especially in the Yellow River source area, China. Therefore, it is imperative to investigate the coupling relationship between soil pH and NPP of the area. The study coupled MODIS reflectance data (MOD09A1) with on-site soil pH to estimate spatial–temporal variations in soil pH, explore the response of NPP to soil pH, and assess the extent to which they contribute to grassland ecosystems, thus helping to fill knowledge gaps. Results indicated that the surface spectral reflectance for seven bands could express the geographic pattern of soil pH by applying a multiple linear regression equation; NPP exhibited an increasing trend while soil pH was the contrary in summer from 2000 to 2021. In summer, NPP was negatively correlated with soil pH and there was a lag effect in the response of NPP to soil pH, revealing a correlation between temperate steppes > montane meadows > alpine meadows > swamps in different grassland ecosystems. In addition, contribution indices for temperate steppes and montane meadows were positive whereas they were negative for swamps and alpine meadows, which are apparent findings. The contribution index of montane and alpine meadows was greater than that of temperate steppes and swamps. The approach of the study can enable managers to easily identify and rehabilitate alkaline soil and provides an important reference and practical value for ecological restoration and sustainable development of grassland ecosystems in alpine regions.

Keywords: MODIS; time-lag effect; coupling relationship; contribution index; alpine area (search for similar items in EconPapers)
JEL-codes: I I1 I3 Q Q5 (search for similar items in EconPapers)
Date: 2022
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (2)

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